Foreign intervention in Yemen's chaos has dramatically raised the stakes in the Arabian Peninsula, threatening to expand what is already a civil war into a conflict pitting Iran against Saudi Arabia and an Arab coalition.

U.S.-led warplanes continued to hammer ISIS positions around the pivotal Iraqi battleground city of Tikrit, stepping in at the Iraqi Prime Minister's request to get at what a spokesman called "difficult targets."

Sgt. Bowe Bergdahl told the military he left his unit in eastern Afghanistan in July 2009 intending to walk to the nearest U.S. military outpost to report wrongdoing, believing he could not trust his own commanders to deal with his concerns, according to sources familiar with the Army investigation. It is the clearest indication yet of the motive behind his decision to leave his post.